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Questions tagged [manipulator]

manipulator is a device used to manipulate materials without direct contact.

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How to decide links length of manipulator?

I'm working on pick and place robotic arm with 4 dof. I'm using MATLAB for inverse kinematics. But, I want to know how to decide links length. Say, I have four point in space upto where my robotic arm ...
Naseeb Gill's user avatar
2 votes
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154 views

How can i consider orientation of 6dof manipulator for inverse kinematic?

i been trying to code IK solver for few days, and i finally move the robot to the desired position. However im having hard time to orient the end-effector as i want it. I read the "Robotics ...
Haegu Lee's user avatar
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Find the kinematic parameters using DH by Craig convention

I am trying to find the kinametic parameters using the J. Craig of the DH parameters for the following 2-DOF robotic manipulator. where $\ x,y $ are the axes of the reference frame and $\ q_1 , q_2 $...
Teo Protoulis's user avatar
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Developing world-frame Jacobian using product of exponentials [closed]

I am going through different texts (Spong Robot Modeling and Control, Murray Mathematical Introduction to Robotic Manipulations) and I am seeing different Jacobians developed for the same RRRP ...
NLhere's user avatar
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Can workspace of a manipulator change after considering its dynamics?

As per my knowledge, the workspace of a manipulator can be determined if one knows the forward and inverse kinematics. But is it possible that the workspace of the manipulator can change after ...
Omkar Paranjape's user avatar
1 vote
1 answer
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How can serial manipulator have unique condition number for given end effector position?

I am reading about Condition Number which is considered as measure of manipulability of robotic arm, it is defined as $$ k = \parallel J \parallel \parallel J^{-1} \parallel $$ Where, $$ \parallel J \...
Siddhesh's user avatar
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Validation of dh parameters

I am working on a concept of robotic arm for which I have fixed DH frames and parameters. Is there any way to validate the correctness of DH parameters and frames ?
Siddhesh's user avatar
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How to obtain the Jacobian matrix for this 2Planar without differentiation

Take a look at the below picture, I would like to derive the Jacobian matrix without differentiation. In this Modern Robotics book, the screw theory is used. I've derived the forward kinematic using ...
CroCo's user avatar
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Forward/inverse kinematics and transformation matrices

I have found the homogeneous transformation matrix that can be used to determine the relation between the parent and child links of a robot. This matrix is shown below. $T_i = \left[\begin{array}{ c ...
user463102's user avatar
1 vote
1 answer
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My Pick and Place Program Not Working

hope you are all well. I am trying to finish a capstone project on Coursera. It asks me to carry a cube object from an initial position to goal. This video shows the movement. Project website: http://...
kucar's user avatar
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How do I find the minimum time for computing a trajecotry for a robotic arm?

I am studying robotics and I am focusing on trajectory planning. I have been struggling with this topic for a while, and I still have some doubts that I cannot solve. One of them is the following: I ...
J.D.'s user avatar
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How to check reachability of manipulator to a point?

I have written a MATLAB code for inverse kinematics of 3R robotic arm, which returns value of joint angles for given link lengths and end effector position and orientation. But if location of point is ...
Siddhesh's user avatar
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Calculating the singular configuration of a 3 revolute joint manipulator

I would really appreciate it if somebody could help me calculate the singular configuration of this simple manipulator I am confused since J is a 2x3 matrix and I cannot simply calculate the ...
Tasos Kontaxoglou's user avatar
1 vote
2 answers
1k views

Different methods to determine DOF: Chebychev-Kutzbach-Grubler method vs. Screw method

I'm familiar with Chebychev-Kutzbach-Grubler method to determine degree of freedom of a robot arm. But it seems this method fails to calculate the mobility of some parallel robots, as explained here. ...
sci9's user avatar
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Robot Graphical Representation in Real Time

I'm working with a robot intended to be placed in a tele-echography environment. To control the robot I'm using a 6D space mouse that control each degree of freedom of the robot. However, since the ...
Miguel M.'s user avatar
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2 answers
5k views

Difference between Degrees of Freedom (DOF) and Degrees of Motion (DOM)

What is a difference between degrees of freedom (DOF) and degrees of motion (DOM)? I know that DOF is the number of independent movements a manipulation arm can make and robot system can have max 6 ...
Mateusz's user avatar
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Why is a joint space trajectory unable to deal with operational space obstacles?

I have found several sources that state that a Joint space trajectory model is not capable of dealing with obstacles in the manipulator workspace. These sources include: slide 10 of "Manipulator ...
user463102's user avatar
1 vote
2 answers
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Parallel spatial mechanism - DOF

The parallel mechanism is composed of a moving platform and a base (or frame) connected by four legs. Each leg is composed of five revolute joints numbered 1, 2, … 5 from the base to the moving ...
Lewis Paterson's user avatar
1 vote
2 answers
113 views

Problem defining rotation matrix

I am studying robotic kinematics , and given the following manipulator with its D-H frames assigned: I have to find the rotation matrix $R_{e}^{2}$, which is the rotation matrix of frame $e$ with ...
J.D.'s user avatar
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2 answers
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Effiecient computation of coriollis matrix

I want to perform kinodynamic motion planning on a 6DoF hybrid manipulator. I calculated mass matrix, coriollis matrix etc using the lagrangian method. The coriollis matirx was calculated symbolically ...
user23335's user avatar
1 vote
1 answer
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Urdf as a way to model dynamics?

Since urdf format serves the purpose of kinematic model but also extends for dynamical properties such as mass,moment of inertia and centre of masses, can it be considered a viable dynamical model of ...
Abhishek Dhyani's user avatar
1 vote
2 answers
2k views

Why does the Denavit-Hartenberg representation fail to capture the length of the last link in my model?

The length of the last link (1.73) of my model (of a human finger) is not represented in any of the parameters that I calculated using the Denavit-Hartenberg algorithm, which I think can't be right. I ...
user avatar
1 vote
2 answers
1k views

how to make a configuration space of a robot manipulator?

How to make a configuration space of a robot manipulator from a work space ? it's robot manipulator is 3 degree of freedom. Is a robot manipulator with more degrees of freedom the same process ?. Do ...
Diego Gonzalez's user avatar
1 vote
2 answers
4k views

How to find the body jacobain, for each link in a robot manipulator?

The links twist could be obtained, and thus The spatial manipulator Jacobian could be done, but when it comes to the body Jacobian, it is becomes difficult. Moreover, the adjoint transformation ...
AlFagera's user avatar
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Standard Notation/Name for Velocity Transformations

I've been looking to see if there's any standard notation for a matrix to convert an end-effector velocity vector $\xi_n^0 = \begin{bmatrix} v \\ \omega \end{bmatrix}$ from one frame of reference to ...
LadyGodiva2's user avatar
1 vote
1 answer
222 views

Feed-forward controller with lookup table

does anyone have experience in implementing a feed-forward controller for a hydraulic cylinder? Often, when a hydraulic cylinder is controlled with PWM values, people (https://drive.google.com/file/d/...
Joe's user avatar
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1 answer
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How to calculate holding and operating torque at the base?

Could anyone please help me with the formula to calculate the operating torque and holding torque at the base to rotate the structure on top of it as shown in image with white arrows? Thank you in ...
Wreck's user avatar
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1 answer
788 views

Multi-Link Robot Degrees of Freedom

I want to compute the DOF of this system if it composed of (n) such links grasping this common object using Grubler's formula obtaining the solution as a function of (n), considering this to be a ...
Ammar Taha's user avatar
1 vote
1 answer
88 views

Dexterity calculation with dual quaternions

How can the manipulability of a robot arm be calculated when the kinematics are described with screw theory such as dual quaternions? These methods are sigularity-free, but what could we say about ...
hamedmh's user avatar
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1 answer
70 views

What is the difference between multi-link flexible manipulators and continuum robots?

I read the review[1] on flexible manipulators, the modeling method of multi-link(even if single-link) flexible manipulators seems very different from the continuum robots like OctArm(multi-section), ...
lumw's user avatar
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735 views

Number of inverse kinematics closed form solutions for ABB IRB 140

I've read that 6 dof manipulators give eight closed form solutions, according to a paper. What is the number of iK solutions for the ABB IRB 140? (last three axes intersect but there is a offset ...
Giannis D's user avatar
1 vote
1 answer
569 views

Rostock Delta Robot 3D Printer Degrees of Freedom (DOF)

What is the degrees of freedom (DOF) of the Rostock delta robot 3d printer (delta mechanism that consists of three prismatic joints)? Here's the link to the delta mechanism I'm referring to: https://...
Hoag Seki's user avatar
1 vote
2 answers
291 views

Optimal trajectory for manipulators using optimal control

I'm trying to implement direct-multiple shooting method to my problem. ...
user70299's user avatar
1 vote
0 answers
23 views

Designing the kinematics and Dynamics of a spherical joint as 3 revolute Joint

I am working on a project where I am trying to mimic human like motion and for that I am designing a 7 DOF arm with the spherical joint in shoulder as 3R joints and 2R joints for elbow and 2R joint ...
Anshul Nayak's user avatar
1 vote
1 answer
79 views

UR robots always have 2 parallel axes. Why not at a singularity?

I thought I understood the Jacobian and singularities pretty well, but then I was asked: UR robots (and others) have 2 joints that are always in parallel. Doesn't this put the robot at a singularity ...
AndyZe's user avatar
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47 views

Grasp matrix implementation

I've majorly followed Dex-net implementation to calculate a grasp matrix (G) to compute other grasp quality metrics (e.g., Ferrari Canny L1 metric or smallest singular value of G). Based on my ...
HOJUN LEE's user avatar
1 vote
1 answer
506 views

How to calculate operating torque and holding torque of a slew drive for a manipulator arm?

Hope you are doing good and enjoying your weekend. I have a question regarding calculation of torque and tilting moment for a slew drive. Slew drive (motorised) will be used at the base of a ...
techno's user avatar
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1 vote
1 answer
119 views

homogenous transformation matrix variants

I am working on some manipulator projects and come across a few variants of the homogenous transformation matrix. I've been working on matlab and they give slightly different answers. Assuming both ...
trex98's user avatar
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1 vote
1 answer
99 views

C space for R5 manipulator

Trying to create a collision avoidance model (RRT) for an RRRRR manipulator. I am unable to wrap my head around how to represent the same in configuration space. Anything upto 3 joint variables is ...
user27243's user avatar
1 vote
0 answers
45 views

Robotic Platforms Similar to the PiBot(Locobot)

I am brain storming platforms to use for a project I am working on. I'm looking for an mobile platform with a manipulator attached. I originally was focusing on the PiBot, but after doing some ...
neerbasu's user avatar
1 vote
0 answers
538 views

Jacobian Derivative (Analytical?)

If I understand this correctly, given the Jacobian Derivative $\dot{J}(q)$ derived using the method presented from the paper by (Rhee, J. Y., & Lee, B., 2017) where the algorithm summarized ...
Spaceman's user avatar
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0 answers
56 views

What is canonical grasp?

What is a canonical grasp and how is it different from normal/other grasp? I've searched through internet and forums but haven't found any answers.
paul-shuvo's user avatar
1 vote
0 answers
59 views

Task Space Control Parameters for 6-Dof Manipulator

I'm developing a Task Space controller based on speed for a Universal Robot 5. I've already calculated the Jacobian, position and rotation error for the classic control method: The method works fine ...
Felipe Henrique's user avatar
1 vote
0 answers
26 views

Control Algorithms for Kinesthetic Teaching

There are several algorithms for post-processing of kinesthetically demonstrated motions for manipulators learning a task. However, I have failed to find papers/research work on modeling the ...
Akshay Kumar's user avatar
1 vote
0 answers
88 views

Cloth (non-rigid body) manipulation with computer vision? [closed]

I am currently working on a prototype device to automate cloth ironing task. So basically the mechanical design involves 4 manipulators and a separate manipulator arm with a hot pad (iron) to ...
Vino's user avatar
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0 answers
106 views

VAL language and velocity control of industrial robot

In my bachelor, I programmed CNC machines. Now, working with an Industrial robot arm, I learn that their programming languages are mostly similar. VAL is a typical example, for instance: ...
Shawn Le's user avatar
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1 vote
0 answers
191 views

Dynamics of parallel manipulator

My task is to apply forces to control 3-dof parallel manipulator. Forces are applied to linear actuators, friction is neglected. End-effector of a robot is supposed to follow generated path; for ...
hedziu's user avatar
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0 votes
2 answers
205 views

What does "resolution of a sensor" mean? [closed]

I am studying robotics and I am focusing my attention on the sensors used on robot manipulators. I have seen that there a proprioceptive sensors, such as encoders, and exteroceptive sensors, such as ...
J.D.'s user avatar
  • 479
0 votes
1 answer
105 views

Visual-Positioning Method

I'm working on mobile manipulator and trying to do visual-positioning of the end-effector. My camera will located around 1-2 meters from the robot. I'm sure i cant use color tracking method because ...
Albert H M's user avatar
0 votes
1 answer
61 views

Definition of robotics manipulator?

I'm new to robotics, I don't understand the way wikipedia defines robotics manipulator. If there is no any direct contact how could the robot move things within his work envelope. In robotics a ...
Henok Tesfaye's user avatar